The invention pertains to a suspension system for a mower conditioner header adapted for cutting crop material, preferably at a set height from the ground. The suspension system attaches the mower conditioner header to a frame. The frame can be adapted to be pulled by a towing vehicle, typically a tractor. It can also be the chassis of a self-propelled machine. In either case the header is propelled along the ground maintaining a constant clearance to cut the crop a constant height, and thus must be capable of following the topography of the ground. Suspension systems have been developed that allow headers to move relative to their supporting frames. Many patents have been granted on various aspects of these suspension mechanisms.
One critical aspect of the suspension system is the ground pressure, the force of the header against the ground. A very low ground pressure can result in excessive bouncing wherein the crop will be cut in an uneven manner whenever the header bounces off the ground, and is thus undesirable. A very high ground pressure is also undesirable as it may cause the header to gouge the ground or it may cause damage to the header when it encounters an obstacle.
Many of the prior art suspension systems have utilized extension springs to suspend a portion of the weight of the header and control the ground pressure. The most desirable ground pressure is set with the header in the operating position. As the header is raised from that position, as would happen when encountering an obstacle, the extension springs typically utilized in the suspension systems, become shorter and the ground pressure quickly increases. Many of the prior art suspension systems utilize extension springs directly connected between the frame and the header.
Mechanisms, which utilize a rocker arm, have been developed to achieve improved load characteristics. In U.S. Pat. No. 4,099,368 a rocker arm and extension spring mechanism is disclosed, mounted to the side of the header and connected to the header via cables. In U.S. Pat. No. 4,313,294 a rocker arm and extension spring mechanism is disclosed, mounted behind the header.
Both these references disclose mechanisms developed to be adapted to headers that are supported by a frame, which is located behind the header, wherein the frame effectively pushes the header along the ground.
An alternative is to support the header from the top, allowing the frame to basically pull the header over the ground an example is disclosed in U.S. Pat. No. 5,107,663 and U.S. Pat. No. 5,060,462. This suspension system offers advantages in that when the header encounters an obstacle it tends to move backwards as it is forced upwards, due to the arrangement of the supporting links. This arrangement results in limited available space for the suspension system.
There remains a need for a suspension system, adapted to a mechanism which supports a header from above, which provides improved suspension characteristics and adjustment features.
According to the present invention there is provided a suspension system for a top supported mower conditioner that provides an improved load profile while packaging all the components in an area that does not interfere with any functions of the machine. This improved load profile includes improved consistency of the ground pressure as the header moves from the lowest, operating, position to a raised, deflected position.
According to a further object of the present invention the lowest position of the header relative to the frame is easily adjusted to control the cutting height of the machine.
According to a further object of the present invention the load profile of the ground pressure is balanced, substantially equal across the width of the header, even though the header is unbalanced.
According to a further object of the present invention a shipping configuration is provided wherein the header is locked into position with the frame.
According to a further object of the present invention the orientation of the header relative to the frame is easily adjusted.